MUlti-Phase Particle Integrator

A complete numerical description of galaxy formation in a cosmological environment has still to be developed: the physical processes involved in star formation act on scales (<1 pc) that are too small to be resolved in simulations describing the cosmological environment (> 1 Mpc). So, such processes need to be included in simulations as sub-resolution effective models.

In this framework, we developed MUPPI, a sub-resolution model for star formation and feedback, loosely based on the earlier semi-analytic multi-phase model of the inter-stellar medium (ISM) by Monaco (2004).

Main characteristics:

• MUPPI is implemented in the Gadget code.
• The ISM evolution is described by a system of ordinary differential equations that drives mass and energy flows among a cold gas phase, a hot gas phase and a stellar component inside each particle.
• The system is integrated with an adaptive Runge-Kutta integrator within the SPH time-step
• The energy resulting from SNe is re-distributed to neighbours; thermal energy is given to the hot phase, whose long cooling time ensures that it is not immediately radiated away.
• Kinetic energy is distributed in a similar way to a much more limited set of particles, so as to trigger massive outflows.
• In cosmological runs the overhead due to MUPPI is around 15%.

Papers:

• Physical regimes for feedback in galaxy formation, P. Monaco, 2004, MNRAS, 352, 181, On the destruction of star-forming clouds, P. Monaco, 2004, MNRAS, 354, 151
• A sub-resolution multiphase interstellar medium model of star formation and SNe energy feedback, G. Murante, P. Monaco, M. Giovalli, S. Borgani & A. Diaferio, 2010, MNRAS, 405, 1491.
• Schmidt-Kennicutt relations in SPH simulations of disc galaxies with effective thermal feedback from supernovae, P. Monaco, G. Murante, S. Borgani & K. Dolag, 2012, MNRAS, 421, 2485.
• A Warm Mode of Gas Accretion on Forming Galaxies, G. Murante, M Calabrese, G. De Lucia, P. Monaco, S. Borgani & K. Dolag, 2012, ApJ, 749, L34
• The Aquila comparison project: the effects of feedback and numerical methods on simulations of galaxy formation C. Scannapieco, M. Wadepuhl, O.H. Parry et al., 2012, MNRAS, 423, 1726.
• Simulating realistic disc galaxies with a novel sub-resolution ISM model, G. Murante, P. Monaco, S. Borgani, L. Tornatore, K., Dolag & D. Goz, 2015, MNRAS, 447, 178.
• Properties of barred spiral discs in hydrodynamical cosmological simulations, D. Goz, P. Monaco, G. Murante & A. Curir, 2015, MNRAS, 447, 1774.
• Galactic outflow and diffuse gas properties at z ≥ 1 using different baryonic feedback models, P. Barai, P. Monaco, G. Murante, A. Ragagnin & M. Viel, 2015, MNRAS, 447, 266.